Is there a way to hack an A/V receiver to eliminate the sound field part? Just direct without the DSP?
I have a Sony STR-DE625 that is 100x2 stereo and 100x5 surround. So obviously the other 3 channels only put out juice when some kind of Dolby sound field is being produced. I'm basically trying to make a 100x5 power amp on a budget of $0
See if it has a setting called "5CH Direct" or Multi Channel In or similar. My DE-995 has it. You would have to have an input on the back for all the channels, mine are RCA as I recall. They let you use an external Dolby/THX/etc processor.
Are you looking for 5 discrete channels or just 5 channels of the same program?
Just looked, you should be able to use Multi-Channel-In with an STR-DE625. The manuals are online and available for download. The pics I found of the receiver shows inputs for multi channel in. This allows for 6 discrete channels, with one (subwoofer) being just a pass through since the sub runs an external amp.
93gsxturbo said:Are you looking for 5 discrete channels or just 5 channels of the same program?
Same program. This is for the theater as a temporary solution. We're doing one musical in the black box this season and I'm trying to avoid renting audio. I figured if I could get 100w to four cabinets of the same mono program to handle vocals I'll be happy..
I got a grant for new wireless body mics (the FCC sold the band we had) so I'm set on speakers, mics, and a fair console, just no amp. The obvious solution is to spend $600 on a couple Crowns or QSCs, but we're in triage mode on the funding side.
93gsxturbo said:Just looked, you should be able to use Multi-Channel-In with an STR-DE625. The manuals are online and available for download. The pics I found of the receiver shows inputs for multi channel in. This allows for 6 discrete channels, with one (subwoofer) being just a pass through since the sub runs an external amp.
So instead of using the onboard DSP, they let you have an external processor split it up and then you can just use the receiver as an amp? Sounds like a logical solution.
Do you think the power supply will handle it?
Oh... another thought.
So let's say I use the direct and put 4 signals in (fronts and rears). That leaves the "B" speaker outputs available (which I assume are parallel with "A" when the selector is set to A+B and obviously shares wattage with each other). So help me understand how the electrons play with each other. This is a theory question on how amps work.
Let's say I were to hook up two small monitors in the dressing rooms and hook them to "B". Will I now be sending half the juice to A and half to B, or will the monitors only draw what they "need?" I'm wondering if I put monitors on B, will the program speakers hooked to A suddenly be significantly quieter, or since the monitors are just little 5-1/4" drivers I won't notice a difference.
Another thought. What if I were to just use stereo and put two cabinets in parallel on each front A channel for 4ohms to up the wattage of the receiver? The manual says I can use 4ohm drivers, but is that only if I change the dip switch to protect the receiver? It says 4 ohms can be used, but is it actually 4-ohm stable, or does that dip switch just add 4 ohms to make the receiver "see" 8ohm loads?
Depends on the unit. Most do not have the feature built in. I do have a yamaha with '6 channel stereo' but it does not give equal power to the surrounds. I think breaking out to RCA and using splitters for multi channel may be your only good option. If audio comes from digital, tough luck unless its from a pc, or you use a decoder. I have used my tv's decoder in a pinch and used the rca outs to get decent sound to a stereo.
Everything will be analog. Wireless mics to a console, two XLR out to XLR-RCA adapters and then RCA splitters is the only way I can envision getting 4 RCAs into the 5.1 inputs.
The manual shows me how to hook it up, but doesn't say how to set it to use it as a 5.1 amp. Learning curves.
Ahh, so a mini PA of sorts.
Most consoles have rca or at least unbalanced 1/4'', that might prove less annoying than xlr adapters, unless you already have them on hand. Usually labeled 'monitor' or 'tape out'. Often, the level controls can differ on these outputs, so get aquainted before use.
I keep a tackle box of adapters and plugs from my soundguy days, so I tend to just 'make it work' with whatever spaghetti I have. Just mind your grounds.
My thoughts exactly. I have a good 100' XLR snake (16x4) so I have 4 XLRs going from the booth to backstage. I found These XLR-RCA adapters for $8
Two of those would get me in to the F and R inputs on the receiver.
Then comes the hard part. Hanging a cluster of 18" loudspeakers from the ceiling. 
I think I'll order those adapters and hook them up. I'll drive the crap out of them for the next week to make sure the power supply and cooling fan in the receiver can handle driving big stuff. I don't want a thermal switch kicking off half way through my performances. If it can handle Jimmy Hendrix for a week, it can handle 6 vocal mics for a couple hours
If its rated 100x5 and you are using it in Multichannel direct mode, you *should* get 100W.
The manual and system of tubes makes no mention as to what is going to happen if running through A and B cut available wattage in half.
In reply to Curtis :
The built in fan should be fine if it's in a well ventilated area, but additional air flow around it wouldn't hurt if it's enclosed at all.
Thanks y'all. I'll play with it and see if I can get it to function like its supposed to. Just not sure how to set the DSP to make it accept the four inputs unless its automatic.
My similar receiver has a button just for multichannel direct on the front. Just set it to the AV input and press the button. YMMV and RTFM
Curtis, The unit won't "do" 100w/channel for 5 channels unless it's also marked RMS 20-20khz @ .xxx THD. If your speakers are efficient enough, you should be fine in a 99-seat theater regardless. The big problem might be adapting to XLRs. Your audio ins on the amp are unbalanced. Hopefully the dimmer packs for the lights are shielded. Otherwise it could be hum city. If that happens, use a "ground lift" 3-to-2-prong adaptor on your audio equipment plugs and make sure they all plug into the same outlet at the wall.
Fortunately, no dimmers. All LED fixtures.
These should do the trick, right?
I have an XLR snake running from the booth to backstage, then I can convert to RCA for the last 6"
Actually, run an XLR cable right up to the amp and use the adapter. Otherwise you'll need either male/female RCA cables or female/female adapters. Most RCA cables are male/male. If you really need to run RCAs the last six feet, find an XLR/RCA adapter with female RCA plugs. That will be less parts and less troublesome. The most sano route would be either running XLR cables off the snake straight into the adapter or using line transformers.
That's what I'm planning. XLR out of the snake over to within 6 inches of the amp using those adapters. That makes it XLR for all but the last 6 inches. Since the RCAs on the amp are female, that's why I picked out these so they can plug directly into the amp.
Good. I've seen some rigs where folks don't want to pay for an XLR cable so they run the adaptor straight out of the snake. Unfortunately, this happens mostly in small theater operations as music clubs are on balance more sound-savvy. Also, sound quality in 99-seat theaters is often not the same priority it would be in a music club. Glad you're cleaning up this operation.
I could probably rewire Lincoln center with the amount of XLR I have :)
Met with a really nice guy this morning about some audio stuff. His house is floor to ceiling PACKED with audio stuff. He buys and sells and also repairs. He and I are talking about trading some of my unwanted audio stuff for some more appropriate stuff. He probably had 150 PA speakers in various conditions. Great resource.
I might be able to get an amp or two from him, but most of his amps right now are really old stuff. The only thing I really saw were some ancient Crown amps that were 4U size with analog meters and only 200wrms x 2. Looked like they were the cream of the crop studio/reference amps... in 1984.
My goal at this theater is to really do things right, but budgets mean I have to do it as best as I can with pennies. The last guy just really trashed this place. It was awful. He liquidated all of our lighting fixtures except some really old Parnels, the dimmers are gone, the tools were minimal and old or broken, and he had built himself an "apartment" with wall flats in the bloody lobby and lived here. Nice enough guy, but he really set us back years.
But I have a grant submitted for sound, another cap campaign for $50k worth of light console and LED fixtures, and will be receiving a 48/96 dimmer pack from another theater during their reno. I just spent $13k from a grant for all new wireless body mics (jeez that feels good).
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